[ various questions are raised about the value of diskless/NFS swap ]
Disks _are_ cheap, but I can think of lots of reasons not to have them,
but to still have swap configured.
What about 100 X-terminal-like workstations on a floor?
What about 100 processors in a parallel array? (Or even just 10 or 20
processors?)
What about 100 browser clients in information kiosks?
What about 1,000 ticket (POS) stations?
In these cases, you definitely do NOT want the heat, packaging,
and, most seriously, the reliability problems of a bunch of
distributed drives, especially since it's rare that one would
actually swap.
But, you say, my drive MTBF is 300,000 hours! That's 30 years!
Well, MTBF is widely misunderstood. That's the statistically
projected MTBF during the service life or warranty period, or even
just the initial service period. After the expected couple-of-years
service life, you enter wear-out, and the MTBF changes!! It
eventually gets pretty close to zero as anyone who has worked in
a large site can tell you.